sound coming from both speakers and headphone

It should toggle back to speakers as default when you remove the headphones.

You should see both laptop speakers and headphones, high light headphone and click on Make Default. If the offending component is found and the situation rectified (ie securing loose wires or connectors etc), then all well and good if not you will have to used additional troubleshooting methods (for example, signal tracer, oscilloscope, multimeter) to track down the problem. Both of the latter are basically low-jitter 24-bit/192kHz D-A converters that can be used as monitor controllers as well as headphone amps, so you can connect them directly to any S/PDIF output to provide superlative audio quality for both your speakers and headphones. If you do the steps that JayEff suggested and the hardware checks out good, then right click on the sound icon and choose playback devices. In either case though, as a first step in isolating the problem, after powering up the unit and once the noise is apparent, use a non-conductive tool, such as a plastic spudger, to move wires or components and prod cold/cracked solder joints to see if the sound is eliminated or gets worse. so did you have any external sound interface or so because switching between headphone and internal speaker its a OS proceeder and not related to AE. If only hearing it when there is some level of sound volume applied that would probably point to electrical noise/interference being injected into the audio circuitry.

If have the unit opened up in a dark room, that effect should be readily apparent and the source identified. It seems from your description that you hear this static noise even when the volume is turned completely off which to me could imply that you are getting some kind of electrical discharge, like for example, jumping across from a component to ground shielding or a piece of metal.

Sound coming from both speakers and headphone